1. Field of the Invention
The present invention relates generally to a method of making hollow glass crystalline microspheres (also known as cenospheres), which have selective extractive or ion exchange capability, by impregnation of the microspheres with selective extractants or ion exchangers. The invention also relates to the method of using the prepared microsphere material to remove radioactive nuclides and/or other hazardous materials from fluids (liquid or gas). In particular the microspheres can be impregnated with certain selective ion exchangers that will remove cesium, lanthanides and actinides.
2. Related Art
U.S. patent application Ser. No. 09/721,962, filed Nov. 27, 2000, discloses the method of making an open-cell glass crystalline porous matrix material comprising microspheres from fly-ash.
U.S. patent application Ser. No. 09/721,963, filed Nov. 27, 2000, discloses a method of solidifying liquid radioactive waste and other hazardous waste using the open-cell glass crystalline porous matrix material as a substrate for evaporation. In that method, selected microspheres are molded into porous glass crystalline blocks, and liquid waste is incorporated into the blocks by multiple cycles of saturating the blocks with liquid, and then drying. After multiple loading/drying cycles, a final calcining step completes the process. Metal oxides with a high specific surface area may be added to the blocks prior to the loading step. The metal oxides are used to increase the surface area and are not ion exchangers or extractants.
The use of pumice as a support for ion exchange material is disclosed in a 1939 British patent 506,291. That patent discloses using pumice stone, ground to a fine mesh size, used as a carrier for thin layers of resin ion exchangers.